Fluid-pressure brake



C. C. FARMER FLUID PRESSURE BRAKE Filed Oct. 21, 1926 RESERVIR' EMERGENCY umvlamom CLA/DE C. FARMER AT1-@HNE AUX/l.. l A R Y RESER VOIR NIA/NTA /NING RIESEN VOIR an emergency application' of the brakes, due to the equalization of theI pressure oi all three reservoirs intoV the brake cylinder 7.

In operation, to charge the brake equipment, when the brake pipeV is charged with fluid under pressure,r iiuid from the brake pipe 9 flows into piston chamber 8 of the triple valve device 1, thence through passage 32, past ball check valve 33, through a rest-ricted port 34, and passage 35 into valve chamber 13, which is in constant communication With the auxiliary reservoir 4 through passages 36 and 37 and pipe 38.

Fluid under pressure from passage 36 lovvs through passages 39, 40, and 41 to the tace of the diaphragm head 24, inside ot thebellows diaphragm 25, and moves said head and slide valve 26 against the force of spring 42, `to a position in Which slide valve 26 opens communication from passage 41, through a restricted port 43, to valve chamber 27, and valve chamber 27 being connected tor the emergency reservoir 5, through passage 44 and pipe 45, the emergency reservoir 5 is charged with fluid at auxiliary reservoir pressure, and chamber 21, of the maintaining or control portion, being connected to the emergency reservoir, the diaphragm 16 is subject to emergency reservoir pressure.

Y Then the emergency reservoir 5 is charged to substantially the same pressure as that in the auxiliary reservoir 4, spring 42 moves diaphragm head 24 and slide valve 26 seas to cut oil communication 'from passage 41 to the valve chamber 27.

Fluid at auxiliary reservoir pressure also ilovvs through passages 36 and 39to passage 46, and thence into valve chamber 31 oit `the check valve portion 3. Fluid at auxiliary reservoir pressure, from valve chamber 13 of the. triple valve device 1, is also sup pliedV to piston chamber 28 ot the check valve portion 3, through passages 47 and 43.

Y The fluid pressure being balanced on opposite sides of the piston 29, the spring 49 shifts the piston 29 and slide valve 3() to the position shown, in LAwhich `the slide valve closes'conneictions in the seatI from the emergency reservoir v5 and the maintaining reservoir 6. l A

Fluid vat auxiliary reservoir pressure is also supplied from passage 47 to chamber 17 of the maintaining or control portion 2, wherein it acts against the diaphragm head 14'.

The maintaining reservoir G is charged with Afluid under pressure from the brake lpipe 9, through passage 50, past ball check valve 51, through restricted port 52, and passage 53, thence through port 54, in the 'main slide Vvalve 11 of the triplevalve device 1, and passagesv and 56, vand pipe 57.-

vIn the` releasefposition of the triple valve ldevice1,'the brake cylinder 7 is connecter to the atmosphere through pipe 58. passage 59, cavity 60 in the main slide valve 11 ot the triple valve device 1, and exhaust port 6l.

Valve chamber 18, oi' the maintaining or control portion 2, being connected to passage 59, through passages 62 and 63, is likewise at atmospheric pressure, when the triple Qvalve device is in release posit-ion.

In order to etl'ect a service application ot the brakes, a gradual reduction in the pressure ot the iuid in the brake pipe 9 is made, and consequently in piston chamber 8 ot the triple valve device 1, causing the triple valve to move to service position in which fluid at auxiliary reservoir pressure, in valve chamber 13, flows through the service port 64 into passage 59, and thence by pipe 5S to the brake cylinder 7, causing an application of the brakes.

Fluid. at brake cylinder pressure f rom passage 59, is also supplied through passages 62 and 63 to valve chamber 1S ot the maintaining or control portion 2.

It the brake cylinder pressure, obtained during the service application, is in the proper ratio to the reduction in auxiliary reservoir pressure, and since the auxiliary reservoir is in constant communication with chamber 17 ot the maintaining or control portion 2, the decrease in pressure in chamber 17 and increase in pressure in chamber 13 ofthe maintaining or control portion 2 is such that the maintaining or control portion 2 does not operate, and slide valve 22 remains in the position shown in the drawing.

lf the pressure ot the fluid in the brake cylinder 7, and consequently in chamber 1S ot the maintaining or control portion 2, be comes reduced through leakage to the atiuosphere, the balance of pressures on the diaphragm heads 1'4, 15. and 16, is upset` so that said diaphragm heads operate to shilt the slide valve 22 to the right to a position in which fluid at maintaining reservoir pressure is supplied from passage (S5, past the end of slide valve 22 to chamber 18, and thence to the brake cylinder 7. lVhen the pressure of the fluid in the brake cylinder 7 is thus restored to correspond with the reduced auxiliary reservoir pressure, in chamber 17, the increase of pressure in valve chamber 13 restores the balance of fluid pressures on the diaphragm heads and causes the slide-valve 22 to be shifted to the position in which communication between the maintaining reservoir 6 and brake cylinder 7 is Vcut olf.

The maintaining or control portion 2 will operate, as above described, to maintain brake cylinder pressure against leakage to the atmosphere` until the pressure. ot the iuid in the maintaining reservoir 6 becomes reduced to equal the pressure in the brake llu lill

the equilibrium ot' the pressures neaaeaa cylinder 7,'a'l'ter wh"ich,tl1e maintaining or control portion 2 Willremain inthe position in which the maintaining reservoir 6 is connected to the brake cylinder 7 ,thereby increasing the volumei'rom which leakage from the brake cylinder to the atmosphere takes place, and consequently reducing the rateat which the pressure in the brake cylinder 7 is reduced by such leakage.

fifterthe initial floyv of fluid under pressure `from 'the auxiliary reservoir 2l@ to the `brake cylinder 7, the triple valve device 1 movesto service lapposition, in which it vemains, unlesslater influenced to changeits position by a further change in brale pipe pressure. y

Since inservice lap `position the service port Get, through the main slide valve 11, is closed by the auxiliary slide valve 12, no further lloiv of fluid from the auxiliary reservoir to the brake cylinder can occur, and since the maintainingand auxiliary reservoirsare never connected together except in emergency, the maintaining of brake cylinder pressure, on account ot leakage, can only vdeplete the maintaining' reservoir. The pressure inthe auxiliary reservoir thus remaining constant,` prevents an undesired release of the brake... i i

llt duringa service application of the lnakes,` when the maintaining reservoir passage't is lapped by theslide valve 22, ol the maintaining' or control portion 2, leale age-should occur from passage intovalvel chamber 18'. on accountot leakage between theslide valve 22 `and .its seat, the pressure et `the fluid in chamber `18 and. inthe brake cylinder 7 will be increased, Which will then unbalance the pressures acting on the diaphragm heads la, 15, and 16, so that said heads Will operate to shit't the slide valve 22 to the lett, to a position in which passage 67, from the chamber 18 oli the u'iaintaining or control portion 2 andthe ln'ake cyl inder 7, Will be connected to atmosphere through cavity G8 in slide valve 22, passage titl anda restricted port 7l), thereby'permitting a, reduction in the pressure -in cham ber18 and the brakecylinder 7. rlhe pressure in' chamber 18 is thus reduced, lso that acting on the diaphragm heads 1.4:, 15, and lti'is restored, `and* the diaphragm heads then act to shift thelslide valve22 back to the position in. which communication betvveen the brake cylinder` 7 and the atmosphere is cut oil?.

To produce an emergency application ot the brakes, a sudden reduction in brake pipe pressure is effected, causing the triple valve device l to move to emergency position in the usual manner. Port 71 in the main slide valve 11 of the triple valve device 1 then registers With passage 55 from the maii'itaining reservoir 6 and permits the fluid in said reservoir to l'loiv into valve chamber 13 et' the triple valve device l.

In the emergency position of the slide valve 11, chamber 28 oli' the check valve portion 3 is vented to atmospherey through passages t8 and a7, cavity Gti in the main slide valve 11, and exhaust port 72. The auxiliary reservoir pressure in valve chamber 3l, oi.' the check valve portion 3, then shifts the piston 29 and slide valve 30 against the atmospheric pressure in chamber 28 and the pressure ot' 58 to the brake cylinder 7, wherein a high emergency pressure is developed.

To prevent the maintaining or control portion 2 from operating to vent fluid at this high pressure from the brake. cylinder te atmosphere, in emergency position of the triple valve device 1, as would be the case it a service application had been made,"as `hereinbeore described, thecharnber 17 ot' the maintaining or controly portion 2, is vented to atmosphere through passage 47, cavity G6 inthe main slide valve 11 o1 the triple valve dev-ice 1 and the exhaust passage 72. The pressures then acting on the diaphragm heads 14, 15, and 16, ot'the maintaining or control portion 2, are such as to shift and hold the slide valve 22 in its entreme right hand position, in `vvhich the maintaining reservoir G is connected to the brake cylinder7 by Way of passage 65, and valvechamber 18. andthe exhaust passage G9 is `cut oil from the brake cylinder passage G7.

lecharging the brake equipment and releasing the brakes after a service applica# tion is effected by increasing the pressure of the fluid in the brake pipe 9, which causes the triple vvalve device 1` to move to releasev position, in which the auxiliary reservoir f1 and the `maintaining reservoir G" are rechargedlin the same manner as `when initial Vly charging the brake equipment, as l1ereinbefore described. rllhe brake cylinder 7 is also vented. `to theatmosphere in this posi.- tion. l

llecharging the brake equipment and releasing the brakes after an emergency application, occur in the same manner as after lll) lilo

lll)

a service application except that in addition emergency reservoir is recharged in the same Way as described in connection with the initial charging of the brake equipment.

Having now described my invention, Wh at I claim as neW` and desire to secure by Letters Patent, is

il. In a fluid pressure brake, the combination withabrake pipe, auxiliary reservoir, brake cylinder, and triple valve device operated upon a reduction in brake pipe pressure for supplying fluid from the auxiliary reservoir to thebrake cylinder, of a maintaining reservoir, a valve device for controlling the supply of fluidfrom said main- -taining reservoir to the brake cylinder, and

meansfor charging said maintaining reservoirV with fluid under pressure from the brake pipe through ports controlled by said Vtriple valve device.

2. In a fluid pressure brake, the combination with a brake pipe, auxiliary reservoir, brake cylinder, and triple valve device having aA piston and slide valve and operated upon a reduction in brake pipe pressure for supplying` fluid from the auxiliary reservoir tothe'brake cylinder, of a maintaining reservoir, a valve device'for controlling the supply of fluid from the maintaining reservoir to the brakexcylinder, and means for charging said maintaining reservoir with fluid under-pressure from the brake pipe through ports controlled bysaid slidevalve.

.3. In a fluidfpressure brake, the combination with a brake pipe and a brake cylinder, of `a maintaining valve device subject to fluid under pressure varying in accordance with variations in brake pipe pressure and operated upon a reduction in brake cylinder pressure for supplying fluid to the brake cylinder and upon an increase in brake cylin'der pressure for venting fluid from the brake cylinder.

4f. In a fluid pressure brake, the combination With a brake pipe and a brake cylinder, of a maintaining valve device subject to fluid under pressure varying in accordance with variations in brake pipe pressure and operated upon a reduction in brake cylinder pressure through leakage for supplying fluid to the brake cylinder to compensate for the leakage and operated upon an increase in brake cylinder pressure through lleakage of fluid under lpressure into the brake cylinder, for'venting fluid from the brake cylinder. j

5. `In a fl-uid pressure brake, the combination with a brake cylinder, brake pipe, auxiliary reservoir and anv equalizing valve device operated upona reduction in brake pipe pressure for supplying fluid from the auxiliary reservoir to the brake cylinder to provide a pressure in the brake cylinder having a predetermined ratio to the reduction in brake pipe pressure, of a maintaining valve device operated upon leakage from the brake cylinder varying said ratio for supplying` fluid to the brake cylinder and upon leakage of fluid under pressure into the brake cylinder varying said ratio for venting fluid from the brake cylinder.

In a fluid pressure brake, the colnbination with a brake cylinder, auxiliary reservoir, and a triple valve device for controlling the supply of fluid under pressure from the auxiliary reservoir to the brake cylinder`r of a maintaining valve device comprising movable abutments subject to the pressures of the auxiliary reservoir and brake cylinder and a valve operated by said means upon a reduction in brake cylinder pressure below a predetermined pressure relation with respect to the auxiliary reservoir pressure for supplying fluid to the brake cylinder, and upon'an increase in brake cylinder pressure above the predetermined pressure relation to vent fluid from said brake cylinder.

7. In a fluid pressure brake, the combination with a brake cylinder, of a maintaining valve device for maintaining the pressure in the brake cylinder against leakage in a service application of the brakes and having means for Vventing fluid from the brake cylinder upon an increase in pressure in the brake cylinder due to leakage of fluid into the brake cylinder and means for preventing said valve device from venting fluid from the brake cylinder upon an increase in brake cylinder pressure in an emergency application of the brakes.

8. In a fluid pressure brake, the combination with 'a brake cylinder and auxiliary reservoir, of a maintaining valve device subject to the pressures of the auxiliary reservoir and the brake cylinder and operated in a service application of the brakes at a predetermined ratio between the auxiliary reservoir pressure and the brake cylinder' pressure for supplying fluid to the brake cylinder and at another predetermined 'atio between the auxiliary reservoir pressure and the brake cylinder pressure for venting fluid from the brake cylinder, and means operating in an emergency application of the brakes for preventing said valve device from venting fluid from the brake cylinder.

In testimony whereof I have hereunto set my hand.

CLYDE C. FARMER. 

